The Grown Up
by TheLazyBAMF
Summary: How could he let this happen? How could he have been such an idiot? He was supposed to be the smart one yet here he was. Some people made wrong orders of coffee for their boss, others forget to carry the one in the equation, why were his mistakes so grand? Or just a short insight on how Mycroft feels on certain parts of the series. Cross-posted on ao3


**Disclaimer: I own nothing!**

 **A/N: Cross-posted on AO3. This was written just after the s4 finale. Any feedback is appreciated, hope you enjoy!**

Eurus was the smart one, Sherlock was the caring one. Two cute children that stole the hearts of everyone that met them. Then there was Mycroft. The smart yet caring elder brother. He was quiet with other people, letting them ignore him in favor of his siblings. He was used to that. Only a fool would think him smart and only the blind would find him handsome. Compared to his sibling of course, he was not an imbecile.

He noticed before then that Eurus was something special. He would later correct himself and call her dangerous but that would come later. Mycroft used to tell stories to his sibling back then, before they learned themselves and enjoyed the independence of not rellying on someone for information. The two children would lay next to him on his bed as he read, sometimes even falling asleep and trapping the elder Holmes in the middle.

 **"They would be angry. They might hate you for it."**

 **"I understand."**

 **"They may never forgive you."**

 **"It's better this way."**

He begged her to tell them. He tried to deduce it from her. He tried to decipher the song, going over it every hour of everyday. But it made absolutely no sense. He tried everything to make his sister answer the questions they needed answers to. He looked for days on end for any clue as to where little Victor was. Sherlock was inconsolable, Mycroft stayed with him during the night when his cries would keep the elder awake.

Then came the fire.

 **"You don't have to do this. I understand what you're feeling but this is not your responsibility."**

 **"She's my sister."**

 **"And she's their daughter. Surely you see how upset they'll be when they find out."**

 **"They won't."**

Their home was on fire. He remembered the strong smell of burning wood, the smoke choking him as he ran outside his bedroom.

"Mummy! Daddy!"

He yelled, coughing at the end as the smoke made his eyes water.

"Mycroft, go get Sherlock. I'm going to get Eurus!" Father was the faster of them thus it made sense for him to go to Eurus' room further down the hall. Mycroft opened his brother's door, sighing in relief as he saw the boy safe. Sherlock was awake, too afraid to go out in fear of being burned by the flames.

"Sherlock, grab your blanket and come with me."

Sherlock did as he was told. Mycroft wrapped him in the blanket, covering his mouth and nose.

"What about you, My?" Sherlock spoke as he raised his head.

"I'll be alright." He lied, his throat was oh so dry and his breathing was labored. "Let's go."

He ran as fast as he can. Adrenaline pumped through his veins, he could hear the firetruck in the distance. He jumped down the stairs, and out the door. He saw his mother in the verge of panic a few feet away and called for her.

"Oh thank goodness you're both safe!"

She hugged them both, tears streaming down her eyes. "Where's father?" Sherlock asked, his eyes going back to the burning building.

"He's getting Eurus. Don't worry. They'll be out in a few."

Mycroft saw how she was trying to calm them but didn't say anything. He gazed back at the house they've lived in for as long as he could remember. He saw the signs, he knew that Eurus started the fire. It was obvious. The fire consumed everything and just as Siger ran out with Eurus, the fire department finally got there.

The heat from the flames, the smoke in his lungs, the adrenalin leaving his sytem. He would be inclined to tell anyone that would have asked that no, he was not tearing up just because their home was burned. It was just all the smoke.

 **"She's dead."**

 **"How?"**

 **"She started another fire, one she did not survive."**

 **"You're lying to me."**

 **"Yes. And that's also the lie you'll be telling your parents. If they know what I'm doing, they'll interfere. Things will get messy."**

 **"I understand. But must I be the one to tell them?"**

 **"You're their son."**

It was a tiring day to say the least. From his sister's fake death, to Sherlock's inability to process his emotions, to his parent's tear-filled apologies to the daughter that will never hear them.

Mycroft stood tall, his family was grieving but here he was, another burden lay against his shoulders. He would have to monitor his siter in a few years to replace Uncle Rudy. He knew everything but he can't tell his family or they'll be more devasted. He can't have Eurus getting someone elses killed.

Throughout the ordeal, Mycroft was the pillar of strength. The funeral was difficult but bearable. He could hear all the whispers in the back but never tried to entertain them.

The night after, Sherlock cried himself to sleep and didn't get up till three in the afternoon. Mycroft's heart dropped as his brother asked him a question as he heard theur mother crying about someone.

"Who's Eurus?"

It was about time he tried the cigarette pack his uncle gave him.

 **"Caring is not an advantage, Mycroft."**

 **"I know."**

 **"There's a difference between I know and I understand."**

 **"Some would argue they're the same."**

 **"Some people don't worry about the things I do. The things that you'll be doing in the future."**

 **"I know."**

 **"Yet here you are."**

Caring is not an advantage yet here he is. In a hospital chair, waiting for his baby brother to wake up from an overdose. Memories of yellowbeard resurfaced at just the absolute worst moment.

His grip tightened on the umbrella. He was not losing his brother any time in the near future. Not on his watch.

"If you don't want mummy to know, you will make a list of everything you've taken."

"Stop having me followed."

"Fine."

* * *

Many people know what happened next. There's a blog detailing the experience and adventure of the boys. What most people don't know was that Mycroft Holmes always had eyes and ears on those boys.

While maintaining his ice cold persona, he was still worrying about his baby brother. Taunts, insults, bickering. All of this was his way to make sure that he was still alright. He added potential trigger words to monitor him when he was younger, which of course helped to strain their relationship.

 **"You know how it all upsets mummy."**

His relationship with his parents worsened. One can't maintain a facadé that long without cracking. His theatre instructor would be proud. Father always senses a lie and mummy knew all their tells. It had started to get easier to just avoid them. To not go to gatherings because he could always feel a heaviness in his chest everytime the family gets together.

Overtime, they seemed to recover and he was able to fool himself into thinking that perhaps he didn't make a mistake.

But then he remembers. They'll hate him for it. Eurus once proved her usefulness by predicting terror attacks but that wasn't all. She said something about thriteen that he didn't put much thought off. Perhaps another prediction or just his ears playing tricks on him.

 **"Moriarty wanted Sherlock detroyed and you have given him the perfect ammunition."**

 **"Tell him I'm sorry. Would you?"**

How could he let this happen? How could he have been such an idiot? He was supposed to be the smart one yet here he was.

Some people made wrong orders of coffee for their boss, others forget to carry the one, why were his mistakes so grand? The Woman used Sherlock to sabotage Bond Air, a project that took twenty years was ruined because he puahed Sherlock in her way.

Now came the fall. Sherlock would have to die to save his friends. He had to leave behind the family he gained just because his brother made a wrong call.

Ultimately, Mycroft would be his own downfall.

 **"He should have done better."**

 **"He did his best."**

 **"Then he's very limited.** "

That stung. Every choice he has ever made was for the greater good. He was willing to sacrifice the few to save the many.

But why wasn't he able to think properly? Why did his control slip ever so carelessly? Emotions always make things messy, that's why he tries to get rid of them. But like all things in his life, he fails.

He was sad that his parents were replacing him. He was scared Eurus would hurt more people. It could have gotten her and a lot more people killed if he let her get away. He was remorseful when Uncle Rudy gave him the reins. He was angry when Sherlock started taking drugs. He was suspicious when John and Sherlock became friends. He was frightened when Eurus asked for Moriarty. He was ashamed when Sherlock had to jump because of his mistakes. He was annoyed when he received no thank you when he git his brother out. He was alarmed when Sherlock left the wedding early. He was filled with worry when he heard his brother had been shot. He was resentful when his parents dragged him to their home to celebrate Christmas. He was absolutely mortified when Sherlock shot Magnusses.

Yes, the last one really did a number on him. It was the last thing he wanted for his brother. For him to be a murderer.

Mycroft Holmes has emotions. He just doesn't use them that often. He locks them up, occasioanlly visits them, but they can never go out. If they did, things would get messy.

 **"Well Sherlock? You were always the grown-up."**

And that was the straw that broke the camel's back. He wished Sherlock shot him. It would have been easier for everybody. Not to mention morbidly fascinating to see(well not see) his parents react to his death. His death that was because of their darling daughter.

It was all like a slap in the face. He gave them everything but they didn't want it. His newly escaped emotions that he was trying to rein back in began to fight on who would control his reaction. There was a building pain in his chest. His stomach was in knots. Why couldn't they see? It was all there. He cared for his sister but he couldn't risk the safety of everyone for her. Why couldn't they understand? Uncle Rudy was right.

He remembered Musgrave Hall. Everything was burning. Everything they had was consumed by the fire. He wasn't entirely sure that all of him got out of there. Perhaps that's where he left his heart? His childhood and innocence.

Sherlock looked at him for guidance. Wasn't he always the grown-up?

He shook his head, not willing to meet any of their eyes. He had always been a disappointment. The first born that nobody asked for. The one that always makes the hard choices. The one who everybody thinks would be able to find another way. The one who always lets people down. Perhaps his biggest mistake was being born. He really needs to smoke.

 _"Am I happy too, I haven't checked."_


End file.
